Prevalence Of Allergic Sensitization Research Articles

The health benefits of breastfeeding on the risk of children developing allergic asthma

Background: The nutritional composition of breast milk, coupled with the health advantages of breastfeeding, are reasons that advisory bodies recommend this form of infant feeding as best practice. Evidence investigating the association between breastfeeding and the prevalence of allergies has, however, been highly inconclusive. Research has shown that breastfeeding has a protective effect on the early development of allergic asthma (Kull, 2002), whilst other evidence showed there to be no significant association (Fergusson, 1983). Paradoxically, other research has even shown breastfeeding increases the risk of children developing allergic asthma (Sears, 2000). This systematic review aimed to examine the evidence relating breastfeeding and allergic asthma among children up to 7 years of age. Methods: A systematic review process was utilised. Different terminologies for breastfeeding and allergic asthma were nested; breastfeeding and breast-feeding were combined with either asthma, allergic, atopic or extrinsic asthma and used in four databases; Google Scholar; PubMed; Web of Knowledge and CAB abstracts. The papers identified were compared against pre-defined inclusion and exclusion criteria. The paper must have: an abstract available; been written in English; used objective and valid diagnostic methodology for defining asthma and atopy in children up to 7 years of age and studied comparable groups of children given breast milk or alternative milks. References acknowledged by the selected papers were sourced and subjected to the same inclusion and exclusion criteria. The quality of the research selected was assessed using a scale adapted from the Newcastle–Ottawa Scale (Wells, 2001). An overall judgement of the quality of the research was made by the researcher. The same terminology and the database Cochrane Reviews were used to identify any relevant reviews that had previously been published. Results: One thousand seven hundred and eighty-three papers were identified. Of these, 562 were excluded because of their publication date, their apparent irrelevance based on their title (n = 717) or by use of the defined inclusion criteria (n = 497). This gave a final sample selection of seven papers. Breastfeeding had a protective effect for the risk of developing asthma. Children who had been breastfed for any period were less likely to have developed asthma by 7 years of age than those who had only been given formula milk. This risk reduction was more common among children who had been breastfed for longer periods of time compared with children who had been breastfed for only a short period. There was no significant difference in the prevalence of allergic sensitisation among children who had been breastfed compared with those given artificial milks. Discussion: Breastfeeding helps to protect children up to 7 years of age from developing asthma. Despite advisory bodies promoting breastfeeding for its protective effect on the development of allergies, evidence showed the benefits were not significant in reducing the risk of atopy. Collectively, breastfeeding does not protect against allergic asthma in children up to 7 years of age. It is unfortunate that mothers are being encouraged to breastfeed their infants for its protective effect on the development of allergies when evidence is not significant. Conclusion: There are many benefits of breastfeeding but current evidence does not support its effect on reducing the risk of children up to 7 years of age developing allergic asthma.

Prevalence of allergic sensitization to Russian thistle in Kingston and the South-eastern Ontario catchment area; a retrospective chart review

Background Russian thistle has only recently been identified as a potentially clinically important allergen. In the third phase of the National Health and Nutrition Examination Surveys conducted in the USA (1988 to1994) over 15% of tested individuals had positive skin-test responses to this extract. The rate of skin test positivity to Russian thistle in Canada is unknown. Objective To determine the prevalence of skin test positivity to Russian Thistle in patients from Kingston and the Southeastern Ontario catchment area, and the possible clinical significance of the same. Methods A retrospective chart review was performed to document the rate of sensitization amongst tested patients to Russian thistle extract (Hollister-Steir). Only patients with appropriate histamine responses were included. We collected demographic data in addition to the presence/ absence of relevant clinical symptoms. Results Of 410 charts reviewed, 170 underwent skin testing to Russian thistle. Of these, 17(10%) were positive. Of the test-positive cohort, 47% (8/17) had symptoms that correlated seasonally with the predominant Russian thistle pollen season (August-October). The mean age of skin-test positive individuals was 35.2 years. 82% and 52.9% of these had concomitant positive skin tests to ragweed and birch, respectively, allergens with known cross-reactivity. Conclusions This preliminary evaluation suggests that the prevalence of skin test positivity to Russian thistle in the studied area is approximately 10%, with about half of these individuals reporting correlative seasonal symptoms. Including Russian thistle in routine skin testing panel may better establish the clinical significance of this environmental allergen. This study was approved by the Queen’ sU niversity Health Sciences and Affiliated Teaching Hospitals Research Ethics Board, with no financial interest or funding provided.

The main features of epidemiology and clinical-immunological interactions of infections caused by herpes viruses and opisthorchiasis at residents of Tomsk

To elucidate the epidemiological, clinical and immunological characteristics of infections caused by herpes viruses and opistorhisami in the etiology and pathogenesis of allergic diseases, we examined 350 residents of Tomsk. The high frequency of infection among residents of Tomsk with herpes simplex virus types 1 and 2, in comparison with the average for Russia in all the groups studied. The level of sensitization and the different severity of allergic reactions in the studied sample was 74%. In groups of volunteers infected with opisthorchiasis, the prevalence of allergic sensitization is higher than the group infected with herpes. The combination of allergic sensitization in herpes-infected patients is associated with the risk of recurrent course of infection, ie with the frequency and severity of clinical manifestations of the latter.

Proportional Venn diagram and determinants of allergic respiratory diseases in Italian adolescents

Large variations in prevalence of atopy and allergic diseases are reported worldwide in children, but in epidemiological studies the use of skin prick tests (SPT) and spirometry along with questionnaires is not common in the Mediterranean Area. The present work was aimed at evaluating the prevalence of current asthma (CA), rhinoconjunctivitis (RC), and eczema (E), with atopy and respiratory function, and the role of risk factors for allergic respiratory diseases. A total of 2150 Italian schoolchildren were cross-sectionally investigated through respiratory questionnaire, SPT, and spirometry. A proportional Venn diagram quantified the distribution of CA, RC, and E, stratifying for allergic sensitization to show differences in prevalence of allergic diseases among subjects with and without positive SPT. CA prevalence was 4.2%, RC 17.9%, and E 5.3%. CA and RC increased, while E decreased, with respect to previous local studies. Allergic sensitization prevalence (evaluated as positive response to at least one SPT) was 39.2%. A double Venn diagram identified 15 categories. Atopic CA was threefold more frequent than non-atopic CA. Atopic vs non-atopic RC and E were 9.6% vs 10.3% and 2.0% vs 3.3%, respectively. Atopic vs non-atopic RC associated with CA were 1.6% vs 0.5%; the same figures for RC associated with E were 0.8% vs 1.3%. Asymptomatic atopic subjects were 27.0%. Atopy, RC, parental asthma, and environmental risk factors were associated with CA. Atopy and environmental factors were risk factors also for RC. Asthma and traffic exposure were linked to reduced lung function. Respiratory allergic diseases are still increasing and largely concomitant in Italian adolescents. Atopy is more important for CA than RC. Avoiding exposures to measured environmental risk factors would prevent 41% of current asthma and 34% of rhinoconjunctivitis.

Perennial Allergen-Specific Immunoglobulin E Levels Among Inner-City Elderly Asthmatics

Background. The role of allergen sensitization has been well established among children and young adults with asthma. Some studies have suggested that allergens play a less important role among older patients with asthma. However, whether older asthmatics have a lower prevalence of allergen sensitization than younger adults remains controversial. The aim of this study was to access the prevalence of sensitization to indoor allergens in older compared to younger inner-city adults with persistent asthma. Methods. The authors used data collected as part of a cohort study of inner-city adults with persistent asthma. Sensitization to indoor allergens (specifically Dermatophagoides pteronyssinus, D. farinae, cat, mouse, Aspergillus fumigates, Alternaria, German and American cockroaches) was evaluated by specific immunoglobulin E (IgE) antibodies measured from peripheral blood. Univariate and multiple regression analyses were used to compare ratios of sensitization according to age (≤35, 36–59, ≥60 years of age). Results. Of the 245 patients in the study, 19% were over the age of 60 years. Overall 73%, 61%, and 41% of patients ≤35, 36–59, and ≥60 years old, respectively were sensitized to at least one indoor allergen (p = .01). Multivariate analysis showed that patients ≥60 years of age were significantly less likely to be sensitized (odds ratio 0.32, 95% confidence interval 0.11 to 0.89) compared to younger adults after controlling for potential confounders. Conclusions. Allergen sensitization is less common in older patients with persistent asthma. However, sensitization to any indoor allergen is relatively frequent in the elderly. Physicians should consider routinely accessing exposure and sensitization to these allergens as part of the evaluation of older inner-city patients with persistent asthma.

Association of allergic sensitization with infectious diseases burden in Roma and non-Roma children

The hypothesis whether exposure to certain infections protects from atopy remains equivocal. To further investigate this, we compared serologic markers of infection and allergic sensitization prevalence in Roma children, who live under unfavorable hygienic conditions that facilitate the spread of infections, and non-Roma children who live in the same area. Analyses included 98 Roma and 118 non-Roma children. Serum IgG antibodies for 13 foodborne- airborne- and bloodborne infectious agents were determined, and a cumulative index of exposure was calculated by adding one point for each positive infection. Specific serum IgE to certain common food- and aero-allergens was also tested. and positivity to any of them was defined as indication of atopy. Roma children were found significantly more seropositive for T. gondii, Hepatitis A, H. pylori, HSV-1, CMV, and Hepatitis B (p < 0.0001). Non-Roma children were found more seropositive for RSV and M. pneumonia (p < 0.0001). Regarding the overall prevalence of atopy or the specific IgE responses to the allergens tested, no statistically significant differences were found between Roma and non-Roma children. A positive association of the cumulative index of exposure to infections with atopy was found in the non-Roma children (OR: 1.38, 95% CI: 1.08-1.75, p = 0.01) and in the total population (OR: 1.42, 95% CI: 1.11-1.83, p = 0.01). Regarding the specific infectious agents tested, a statistically significant positive association of atopy with seropositivity was found for M. pneumoniae in the non-Roma children (OR: 3.93, 95% CI: 1.39) as well as in the total population studied (OR: 2.83, 95% CI: 1.32-6.07, p = 0.01). Despite the higher burden of exposure to the battery of the infectious agents tested among Roma children, no protective effect for allergic disease development was evident. On the contrary, a positive association of exposure to infections with evidence of atopy was found, especially evident in the non-Roma children.

Human rhinoviruses, allergy, and asthma: a clinical approach

The prevalence of allergic diseases is increasing in Lithuania as in the world. The prevalence of allergic sensitization is often higher than 50% of the population. The "hygiene hypothesis" proposed that reduced immune-stimulation by infections may have resulted in the more widespread clinical expression of atopic disease. However, it alone does not provide an adequate explanation for the observed increase of allergic diseases. Human rhinovirus infections are the major infections with a worldwide distribution. Viral infections of the respiratory tract are the most common triggers of acute asthma exacerbations. These exacerbations are poorly responsive to current asthma therapies and new approaches to therapy are needed. The aim of this review is to present the current knowledge and clinical implications of human rhinovirus infection in allergy and asthma development and needs for further research. Recent evidence has shown that the immune responses to human rhinoviruses differ between asthmatic and nonasthmatic subjects. Novel insights into the mechanisms of virus-induced asthma exacerbations support the possibility that viral infections may be involved in the epithelial cells damage, inflammation, and airway hyperresponsiveness as well as in profibrotic response and induction of airway remodeling. The data of original investigations support the concept that the immune stimulation by rhinovirus infections contributes to the development of asthma, when an atopic host is infected with human rhinoviruses. Early rhinoviral wheezing is the predictor of subsequent asthma development in high-risk children. Synergistic effect of allergic sensitization, allergen exposure, and viral infection was suggested in the increased risk of hospitalization for asthma in both children and adults. Timing of allergen exposure may be important in a synergistic outcome. The increased susceptibility to rhinovirus infections was identified in atopic asthma. This review also presents the current options on the treatment and prevention of virus-induced asthma. Further studies are needed in order to differentiate between the response to viruses of healthy and atopic or nonatopic asthmatic children and adults. New research data may lead to novel strategies in treatment and prevention of asthma exacerbations as well as prevention of asthma induction.

Time Trends in Allergic Sensitisation and Helicobacter pylori Prevalence in Finnish Pregnant Women

Background: An increase in the prevalence of allergic conditions has been documented in Finland, correlating with the diminishing prevalence of Helicobacter pylori infections. We investigated whether the increase of allergic sensitisation still continues and correlates with the prevalence of H. pylori infections. Methods: The sera from 958 pregnant women in 1983, 1989, 1995 and 2001 were analysed for the presence of antibodies against H. pylori. In addition, allergen-specific IgE antibodies and total levels of IgE antibodies were measured. Results: A clear birth cohort effect was found in the prevalence of allergic sensitization: allergen-specific IgE was more frequent among recent birth cohorts than earlier ones (p = 0.001). The frequency of H. pylori antibodies followed the opposite trend (p < 0.001) and the increase in allergic sensitisation was only seen among H. pylori-negative women. A modest increase was also seen in allergic sensitisation between the 4 time series among the H. pylori-negative subjects (p = 0.04). Total IgE levels did not differ between birth cohorts or time series. Conclusion: The results suggest that hygiene-related environmental factors have played a role in the increase of allergic sensitisation during the last decades.

Familial Aggregation of Skin Sensitization to Aeroallergens in a Rural Area in China

Background: The prevalence of allergic sensitization has increased all over the world during last years and allergic sensitization may be related to genetic or environmental factors or to both. The objective of this study was to estimate the prevalence rates of allergic sensitization and assess the familial aggregation of allergic sensitization to aeroallergens in asthma index families. Methods: The skin prick test (SPT) reactivity to 8 aeroallergens and the SPT reactivity-related risk factors were evaluated. The allergic sensitization was based on SPT. Univariate and multivariate logistic regressive models were used to estimate the effect size (odds ratio, OR) of correlation within families with positive SPT. Results: Of 4,213 analyzed subjects in 1,006 asthma index families, 40.9% had at least one positive SPT, 42.3% in parents (father: 43.3%; mother: 42.3%), 43.9% in first offspring, and 36.0% in subsequent offspring. The most common allergens were Dermatophagoides pteronyssinus (DP), cockroach and Dermatophagoides farinae (DF). Allergic sensitization status of both parents and first offspring was related to the risk of allergic sensitization for subsequent offspring. The OR for the positive (father)-positive (first offspring) group was 1.92 (p < 0.01), 3.26 (p < 0.01) for the positive (mother)-positive (first offspring) group, and 2.12 (p < 0.01) for the positive (father)-positive (mother) group, which were adjusted for age, sex, body mass index, history of asthma and smoking status. Conclusions: Our findings supported a significant familial aggregation of allergic sensitization in this Chinese population and highlighted the role of genetic factors in allergic sensitization.

House dust (1–3)‐β‐d‐glucan and wheezing in infants

(1-3)-Beta-D-glucan is a fungal cell wall component, suspected to cause respiratory symptoms in adults. However, very little is known on the possible health effects of (1-3)-beta-D-glucan during infancy. We examined the association between (1-3)-beta-D-glucan exposure and the prevalence of allergen sensitization and wheezing during the first year of life in a birth cohort of 574 infants born to atopic parents. Endotoxin exposure was included as a possible confounder. (1-3)-Beta-D-glucan and endotoxin exposures were measured in settled dust collected from infants' primary activity rooms. The primary outcomes at approximately age one included parental reports of recurrent wheezing and allergen sensitization evaluated by skin prick testing to a panel of 15 aeroallergens as well as milk and egg white. Exposure to high (1-3)-beta-D-glucan concentration (within fourth quartile) was associated with reduced likelihood of both recurrent wheezing [adjusted OR (aOR) = 0.39, 95% CI = 0.16-0.93] and recurrent wheezing combined with allergen sensitization (aOR = 0.13, 95% CI = 0.03-0.61). Similar trends were found between (1-3)-beta-D-glucan concentrations and allergen sensitization (aOR = 0.57, 95% CI = 0.30-1.10). In contrast, recurrent wheezing with or without allergen sensitization was positively associated with low (1-3)-beta-D-glucan exposure within the first quartile (aOR = 3.04, 95% CI = 1.25-7.38; aOR = 4.89, 95% CI = 1.02-23.57). There were no significant associations between endotoxin exposure and the studied health outcomes. This is the first study to report that indoor exposure to high levels of (1-3)-beta-D-glucan (concentration >60 microg/g) is associated with decreased risk for recurrent wheezing among infants born to atopic parents. This effect was more pronounced in the subgroup of allergen-sensitized infants.

Urban background particulate matter and allergic sensitization in adults of ECRHS II

BackgroundEpidemiological studies have shown weak or inconsistent associations between ambient air pollutants and allergic sensitization. The aim of this study was to evaluate whether regional urban air pollution may partly explain the large variation in the prevalence of allergic sensitization across cities of the European Community Respiratory Health Survey (ECRHS) II. MethodsECRHS is a cross-sectional survey initiated in 29 countries across Europe in the 1990s (ECRHS I) with a follow-up conducted 10 years later (ECRHS II). Subject characteristics were measured by questionnaires and blood tests conducted for the measurement of specific immunoglobulin E. Fine particle mass (PM2.5, <2.5μm) and sulphur on PM2.5 were measured in 21 centres and annual averages of urban regional background air pollution were calculated. Results were scaled by an interquartile range increase in ambient PM2.5 (6.03μg/m3) and sulphur (1336ng/m3). Generalized estimating equations were applied to compute population average effect estimates with adjustment for age, gender, smoking habit, education and number of siblings. ResultsA notable variation in pollution level and prevalence of allergic sensitization was observed. Moreover, exposure to urban regional background air pollution was not associated with allergic sensitization; adjusted odds ratios and 95% confidence interval were 1.02 (0.95–1.09) for PM2.5 and 1.08 (0.86–1.31) for sulphur. These statistically non-significant associations were sensitive to model specification. ConclusionsThe study suggests that regional air pollution measured at fixed sites is not associated with allergic sensitization among adults in ECRHS II.

Association of hepatitis A virus infection with allergic sensitization in a population with high prevalence of hepatitis A virus exposure

An inverse association between allergic sensitization and markers of exposure to food-borne and orofecal infections (particularly hepatitis A virus, HAV) has been reported. The prevalence of HAV exposure and allergic sensitization vary widely in different areas, and vary along with age within a given area. To investigate the association between HAV exposure and allergic sensitization in adults from a mostly rural area of Spain. An age-stratified random sample of 720 subjects was drawn from the population older than 18 years of A-Estrada, Spain. From 697 eligible subjects, 469 (67.2%, median age 54 years, range: 18-92) participated in the study. Positive skin prick tests to a panel of aeroallergens defined allergic sensitization. Positive serum HAV antibodies (assayed in 465 subjects) defined HAV exposure. The prevalence of HAV exposure was 83.6% (95% CI: 80.7-86.5). The prevalence of allergic sensitization was lower in subjects with HAV exposure than in patients without it (25.0%vs 40.0%, OR 0.44, 95% CI: 0.25-0.77, P=0.004), but this association became substantially altered after adjusting for age, which was closely linked to both allergic sensitization and HAV exposure (adjusted OR 1.15, 95% CI: 0.60-2.19, P=0.66). In a population with high prevalence of HAV exposure, no significant association between HAV exposure and allergic sensitization is observed after controlling for the confounding effect of age.

Risk factors for atopy among school children in a rural area of Latin America.

Infection with common childhood infectious diseases including geohelminth infections may provide protection against the development of atopy and allergic disease. Few studies have investigated risk factors for atopy among children living in rural areas of Latin America. To identify risk factors associated with atopy among school-age children in a rural area of Latin America. Analytic cross-sectional study of school-age children conducted in seven rural schools in Pichincha Province in Ecuador. Detailed risk factor information was obtained by questionnaire, stool samples were collected for identification of geohelminth parasites, and Mantoux testing was performed to determine tuberculin sensitization. A total of 1002 children from seven rural schools were recruited. The prevalence of geohelminth infections was high (70.1% were infected with at least one geohelminth parasite) and the prevalence of allergic sensitization was high (20.0% had evidence of aeroallergen sensitization). Factors associated with significant protection against atopy in multivariate analyses were the presence of overcrowding in the child's home, low socio-economic level, and infection with geohelminth parasites, and the protective effects of the three factors were statistically independent. Low socio-economic level, overcrowding and geohelminth infection, are independently protective against atopy among school-age children living in a rural area of Latin America.

Is the increase in allergic respiratory disease caused by a cohort effect?

Changes in lifestyle or environmental factors are responsible for the increasing prevalence of allergic respiratory disease. Establishing the time at which the increase began may provide a clue as to what factors possibly could have contributed to the increase. Many cross-sectional studies have shown that the prevalence of allergic sensitization decreases with increasing age. This could reflect the natural course of allergic sensitization. Alternatively, this could reflect that the increase in sensitization is caused by a cohort effect, i.e. an increase among subjects born during recent decades. The aim was to investigate age-specific changes in the prevalence of allergic sensitization in a cohort of adults. A total of 599 subjects aged 15 to 69 years participated in a cross-sectional general population study in 1990. In 1998 they were invited to a follow-up, and 64.4% (386/599) were reexamined. Serum samples obtained from the participants in 1990 and 1998 were analysed for specific IgE to six common inhalant allergens with the same assay. The prevalence of allergic sensitization (specific IgE to at least one allergen) increased among subjects who were less than c. 30 years at baseline (1990), i.e. subjects born during the 1960s or later, while the prevalence was unchanged among subjects who were more than c. 30 years at baseline. The results support the notion that the increasing prevalence of allergic respiratory disease is caused by a cohort effect. Thus, changes in lifestyle or environmental factors that occurred around or after 1960 may have contributed to this increase.

Increase in the prevalence of allergen skin sensitization in successive birth cohorts.

Little is known about longitudinal trends in the prevalence of allergen skin sensitization in the general population. We sought to measure the change in prevalence of allergen skin sensitization over a 9-year period in a cohort of adults and hence to determine whether cross-sectional differences in prevalence between age groups are due to an aging or cohort effect. In 1991 and 2000, we measured skin sensitization, defined as a wheal diameter of 3 mm or larger than that elicited by a saline control, to Dermatophagoides pteronyssinus, cat fur, mixed grass, Aspergillus fumigatus, and Cladosporium herbarum in a cohort of 1339 adults from Nottingham aged between 18 and 71 years in 1991. Subjects were divided into six 9-year successive birth cohorts, and the effects of birth cohort and the within-subject change from 1991 to 2000 were analyzed in a generalized estimating equation logit model. The unadjusted prevalence of sensitization to any allergen was 30.5% in 1991 and 31.8% in 2000. In cross-sectional analyses the prevalence of sensitization decreased with increasing age at both surveys (risk ratio, 2.15; 95% confidence interval [CI], 1.45-3.17 for 18- to 26-year-old patients relative to 63- to 70-year-old patients in the 1991 survey). In longitudinal analysis there was no within-subject change in sensitization from 1991 to 2000 (adjusted odds ratio, 1.07; 95% CI, 0.97-1.19), but there was a significant cohort effect (adjusted odds ratio per successive 9 year cohort, 1.27; 95% CI, 1.18-1.37). The cross-sectional decrease in allergen sensitization with age in the general population arises predominantly from a secular increase in sensitization prevalence with successive birth cohorts and not to a loss of sensitization within subjects over time. As a result of this cohort effect, the prevalence of allergic sensitization has increased in this general adult population sample.

Longitudinal Changes of Sensitization to Farming-Related Antigens among Young Farmers

Background: We have shown previously that the prevalence of allergic sensitization in Tyrolean farming students is high, with a clear relationship to occupational exposure. Objectives: It was the aim of this investigation to assess longitudinal changes in sensitization and a possible impact on lung function. Methods: Of the 147 farming students in the original cohort, we could re-examine 42 after a mean interval of 4.0 years. All individuals completed a questionnaire and had spirometry, skin prick tests, total and specific IgE analysis, and testing for precipitating antibodies. Results: As compared to the first study, there was a decrease in the frequency of IgE-mediated allergy (30.1 vs. 54.8%; p < 0.05) and in total serum IgE levels (107.4 ± 254 vs. 157.8 ± 304 U/ml; p < 0.001). Conversely, 3 individuals had developed precipitating antibodies de novo, and those who had initially had a positive precipitin test (n = 6) were still positive. A larger-sized estate, the lack of a hay dryer, and the presence of moldy hay were confirmed as risk factors for allergic sensitization. Although there was a slight overall decrease in forced vital capacity, no new cases of occupational lung disease were found. Conclusions: In young Tyrolean dairy farmers, the prevalence of precipitins is constantly high and rising while IgE-mediated allergy declines. Within 4 years, no clinically relevant impact of allergy on lung function was noticed.

Enhanced in vivo IgE production and T cell polarization toward the type 2 phenotype in association with indoor exposure to VOC: results of the LARS study

AbstractThe association between indoor exposure to volatile organic compounds (VOC), prevalence of allergic sensitization and cytokine secretion profile of peripheral T cells was studied in 3 year old children of the LARS study (Leipzig Allergy Risk Children Study) to investigate the role of VOC exposure as a risk factor for the development of atopic disease.Indoor VOC exposure was measured over a period of 4 weeks in infants' bedrooms using a passive sampling system. Specific IgE antibodies to food, indoor and outdoor allergens were measured by the Pharmacia CAP system and correlated to VOC exposure (n = 120). In addition, cytokine producing peripheral T cells (interleukin(IL)-4, interferon(IFN)-γ) were measured in a subgroup of 28 children by means of intracellular cytokine staining.For the first time we were able to show that exposure to alkanes (C6, C9, C10) and aromatic compounds (toluene, o-xylene, m+p-xylene, 2-, 3- and 4-ethyl-toluene, chlorobenzene) may contribute to the risk of allergic sensitization to the food allergens milk and egg white (Odds ratios between 5.7 and 11.2). Moreover, significantly reduced numbers of CD3+/CD8+ peripheral T cells were found in children exposed to alkanes (C9-C13), naphthalene and chlorobenzene. Exposure to benzene, ethylbenzene and chlorobenzene was associated with higher percentages of IL-4 producing CD3+ T cells.Both an increase in IL-4 producing type 2 T cells and a reduction of IFN-γ producing type 1 T cells may contribute to a type 2 skewed memory in response to allergens. Therefore, we suggest exposure to VOCs in association with allergic sensitization to be mediated by a T cell polarization toward the type 2 phenotype.

Similar prevalence of respiratory symptoms and atopy in Estonian schoolchildren with changing lifestyle over 4 yrs.

The prevalence of allergic sensitization and clinical manifestations is low in Eastern Europe, despite a continuous increase in industrialized countries with a market economy. The aim of the present study was to study changes in the prevalence of respiratory symptoms and atopic sensitization over time among schoolchildren in Estonia, in relation to environmental changes as the country transformed into a market economy. A cross-sectional study of 10-yr-old children was carried out between October 1996 and April 1997, employing a questionnaire regarding the prevalence of wheezing, rhinitis and itching rash (n=979) and skin-prick tests with seven inhalant allergens (n=640). The results were compared with those of a similar study performed in 1992-1993. The 12-month prevalence of wheeze was 8.3%, as compared to 9.4% in 1992-1993 (NS) and of asthma was 2.5 versus 3.2% (NS). The prevalence of a positive skin-prick test result was 14.3% in both studies. Furthermore, the prevalence of sensitivity to the individual allergens was similar, except for a significantly higher prevalence of dog sensitivity in 1996-1997 (4.7 versus 2.0%). The prevalence of respiratory and other potentially allergic symptoms, as well as the prevalence of atopic sensitization, remains low in Estonian 10-yr-old children, despite a changing lifestyle over the past 4 yrs. This could indicate that the time period was too short for environmental changes to affect the prevalence of allergy, or alternatively that risk factors associated with a "western lifestyle" are of particular significance earlier in life.

Differences in prevalence of allergic sensitization in urban and rural school children.

Environmental factors are important causes of sensitization, even though the effect of specific pollutants and the interaction between pollution and aeroallergens are not completely known. To evaluate whether the exposure to pollutants or to allergens is a more important contributing factor in causing sensitization. A group of 312 children living in the city and a group of 225 children living in a rural area, ages 11 to 14, were studied. All subjects underwent a skin prick test. The pollen counts were performed in the two different areas during the peak of the pollen season. At the same time the levels of ozone and suspended particulates were measured. The students living in the rural area showed a significantly higher percentage of sensitization than those in the city (P = .046). Sensitization to pollen was more frequent in the rural area (P < .001) but pet sensitization was more frequent in the city. More rural area students were sensitive to multiple allergens (P = .034). Pollen levels were higher in the rural area (P = .001). Both ozone and suspended particulate levels were higher in the city (P = .001 and P < .001, respectively). The degree of pollen exposure is a larger contributing pathogenic factor in inducing sensitization than air pollution.